The present invention relates generally to improvements in vehicle safety belt retractors and it relates more particularly to an improved vehicle safety belt retractor reel mechanism of the type which automatically prevents the extraction of the belt upon the sharp withdrawal of the belt consequent to an abnormal vehicle condition which tends to propel the occupant from the seat.
Many types of safety belt retractor systems are known which normally permit the free movement of a vehicle seat occupant under normal conditions, but automatically lock the retractor against belt withdrawal under abnormal or emergency conditions, which tend to throw the occupant from the seat, such as in the case of a collision or rapid deceleration or vehicle overturning. A well known type of such an automatic locking belt retractor reel which possesses many advantages is of the so called inertia type locking reel in which a sharp acceleration of the belt wind-up reel in the belt extraction direction attendant to a sharp withdrawal of the safety belt automatically locks the reel against further belt withdrawal, thereby safely retaining the occupant in the seat and preventing or minimizing injury. However, this inertia type retractor reel possesses an important drawback in that it responds to rapid belt withdrawal whether intentional and desired, or as a result of emergency. Thus, if the seat occupant does not withdraw the belt for application sufficiently slowly and uniformly, but in a jerky manner, the reel braking mechanism is actuated, preventing adequate belt extraction and requiring a repetition of the belt withdrawal procedure, a practice which is highly inconvenient and annoying, and often results in the seat occupant not applying the safety belt.